[css-ruby] Add note on bidi isolation

Author: frivoal

css-ruby-1/Overview.bs

@@ -922,6 +922,15 @@ Bidi Reordering</h3>
 	the bidi reordering of [=internal ruby boxes=] happens after line-breaking
 	so that content is divided across lines according to its logical order.
 
+	Note: It could be useful to adjust these rules slightly
+	so that when 'ruby-merge' is ''merge'' on a particular [=annotation container=],
+	bidi isolation is not forced onto the individual annotations,
+	enabling them to be processed together.
+	However, this would add complexity to implementations,
+	which does not seem justified in the absence of demand to handle this situation.
+	Anyone with a need for this to be handled
+	is encouraged to contact the CSS Working Group.
+
 	See [[CSS3-WRITING-MODES]] for a more in-depth discussion of bidirectional text in CSS.
 
 	<!-- Some alternate proposals exist in the 2013 draft's comments section. -->